Hemodialysis is widely used to sustain life in individuals without kidney function. The membrane material most commonly used for this purpose is regenerated cellulose. Regenerated cellulose is not completely biocompatible; it stimulates the coagulation and complement systems and may be a cause of both acute and chronic morbidity for the patient. Further, its mass transfer properties are limited, as are methods of sterilization. Substitutes for regenerated cellulose are being sought. In Phase I of this program, the biocompatibility of a number of materials which might replace regenerated cellulose was examined. Two polymers with improved biocompatibility compared to regenerated cellulose were identified. The feasibility of fabricating these polymers into membranes suitable for hemodialysis was also demonstrated. In Phase II, we will determine the casting conditions necessary to produce membranes of the appropriate mechanical and mass transfer properties for hemodialysis from these polymers. The biocompatibility of the membranes will then be confirmed using a model which reproduces the conditions of hemodialysis. The ability of the membranes to retain their properties following exposure to the chemicals used in the multiple use of dialyzers will also be confirmed. Finally, preliminary toxicity testing of the membranes will be performed as a prelude to clinical trials.